The present invention relates to an air intake system of a multi-cylindrical two-bank internal-combustion engine, the cylinder of one bank each being connected by suction pipes to a resonance assigned to said bank, and comprising at least one connecting pipe between the resonance receptacles.
The performance of an internal-combustion engine is directly proportional to the product of its displacement and the mean pressure. When an increase of the displacement, which is unfavorable with respect to the amount of exhaust gas and to fuel consumption, is to be avoided, only a targeted increase of the mean pressure remains as a means to increase the performance. As a result, the torque of the internal-combustion engine is also increased because it is a direct result of the above-mentioned product.
From German Patent Document DE-34 24 433 A1, an air intake system of the initially-described type is known which has two resonance receptacles. These resonance receptacles are connected with one another by two resonance pipes which can be shut off and into which the supplied fresh air flows. From the resonance receptacles, individual suction pipes lead to the intake ports of the cylinder heads. As a function of the connection cross-section of the receptacles controlled by throttle valves, the mean pressure and therefore the torque can be increased in a wide rotational speed range.
An object of the present invention is to improve an air intake system of the intially-described type in such a manner that the mean pressure is increased, if possible, in the whole rotational speed range of the internal-combustion engine.
This and other objects are achieved by the present invention which provides an air intake system of a multi-cylinder two-bank internal-combustion engine, the cylinder of one bank each being connected by suction pipes to a resonance receptacle assigned to said bank, comprising: at least one connecting pipe between the resonance, and suction pipe extensions that are respectively assigned to the suction pipes. These suction pipe extensions extend inside the resonance receptacles and are connected to a common receptacle that has a fresh-air inlet.
When, in the case of an internal-combustion engine, in addition to the two-chamber resonance system formed by the resonance receptacles and the connecting pipe, suction pipe extensions are arranged which, in sections, extend in the resonance receptacles, are assigned to the suction pipes and are connected to a common receptacle provided with a fresh-air inlet, this single-chamber ram pipe system formed by the receptacle and the suction pipe extensions acting as ram pipes, supplements the resonance system such that the volumetric efficiency will rise. This means that a larger amount of fresh air is fed to each cylinder, thereby increasing the mean pressure.
In certain embodiments of the invention, the connecting pipe also has a fresh-air inlet whereby the mean pressure is further increased.
The two fresh-air inlets are advantageously combined in a common inlet opening of the receptacle, in certain embodiments of the invention. This inlet opening may be arranged on the end of the receptacle which extends in the longitudinal direction of the cylinder banks approximately in the center between the resonance receptacles. In this case, the connecting pipe is constructed to be divided, the sections of the resonance receptacles extending to the center receptacle. By means of the center inflow and the direction connection of the connecting pipe and of the suction pipe extension to the receptacle distributing the fresh air, this arrangement permits a low-loss uniform flow.
In certain embodiments of the invention, at least one suction pipe extension of each cylinder bank has a throttle valve acting as a shut-off element. In this case, the air intake system acts as a pure resonance system, these suction pipes extensions acting as switchable additional resonance pipes.
Certain embodiments of the invention further increase the mean pressure and optimize the flow conditions and vibration conditions by mutual alignment of the cylindrically constructed sections of the suction pipe extension which are situated in resonance receptacles. In this case, these have a specified distance from the admission funnels of the suction pipes.
Another optimization is achieved in certain embodiments an arrangement of sliding sleeves on the cylindrical sections, in which case the distance from the admission funnels can optionally be bridged. As a result, the charge effect of this air intake system is improved in a wide rotational speed range because of the fact that, in a low to medium rotational speed range, the sliding sleeves close off the annular gap defined by the distance and uncouple the two-chamber resonance system. As a result, only the single-chamber system is connected, in which case the suction pipe length is increased by the amount of the suction pipe extension and the overall volume of the system is reduced. By the opening of the annular gap at higher rotational speeds, the resonance system is connected, and the suction pipe length is shortened and the overall volume is reduced.
For a further improvement of the resonance characteristics, in parallel to the connecting pipe, certain embodiments of the invention provide a second connecting pipe arranged between the resonance receptacles. For the rotational-speed-optimal connection of the connecting pipes, these embodiments are provided with shut-off elements which are to be actuated as a function of the rotational speed.